This series is divided into three subseries. The first subseries comprises Jeffrey's general research notes. The second subseries focuses on Jeffrey's collaboration with Carnap, largely in the form of correspondence and exchanges of drafts. The third subseries contains Jeffrey's grant applications, awards, and summary reports on concluded projects.

Subseries 1.Research Notes, 1959-1997

Scope and Content Notes:

Jeffrey's research material consists mostly of handwritten and typed documents recording his reflections on subjective probability, decision theory, Bayesianism and related topics, including comments about the works of others. Also featured is a notebook on the Richard Lewontin Lectures that Jeffrey attended while in Harvard in the Fall of 1984.

The files are arranged in chronological order starting with the earliest; undated material is placed at the end of the series in alphabetical order according to folder title.

Carnap and Jeffrey had been close friends and collaborators since Jeffrey studied and received his Master's Degree under Carnap at the University of Chicago. The documents in this subseries reflect this close personal and professional relationship, mainly in form of correspondence with Carnap and his wife Ina, as well as exchanges of drafts and research notes. Carnap often included Jeffrey in his exchanges with other individuals, therefore numerous letters are carbon copies of Carnap's correspondence with others. Also featured are writings on Carnap authored by Jeffrey and others.

The folders are arranged in chronological order, followed by undated material.

Copies of Carnap Articles "Über Protokollsätze", and "Truth and Confirmation"

Subseries 3.Grant Proposals and Projects, 1960-1993

Scope and Content Notes:

This series contains Jeffrey's grant applications, project reports, and related correspondence and paperwork. Included is a project proposal by Hempel and a grant evaluation by Jeffrey of a proposal by Max Black.